Bioabsorbable surgical devices such as, for example, sutures, made from copolymers derived from one or more of glycolide, lactide, p-dioxanone, epsilon-caprolactone and/or trimethylene carbonate are known in the art. However, filaments prepared from certain such copolymers are not dimensionally stable and require a freezing step to maintain a desired physical dimension. See, e.g. U.S. Pat. No. 5,494,620 which discloses the details of and benefits derived from a freezing operation. U.S. Pat. No. 5,403,347 discloses a block copolymer wherein one of the blocks is made from hard phase forming monomers (preferably glycolide) and another of the blocks is made from soft phase forming monomers (e.g., p-dioxanone) copolymerized with randomly intermingled units of other soft phase forming monomers (e.g., trimethylene carbonate)
A surgical suture is either a synthetic monofilament or a braided multifilament structure or alternatively a cut, ground or polished ligature derived from animal intestines, used for tissue approximation or the attachment of an implantable device. Sutures can be made of either resorbable or non-resorbable materials. Resorbable sutures degrade and disintegrate inside the body after exposure to the in-vivo environment in a pre-determined time interval, so there is no need for a second surgery to remove the suture after the tissue is healed at the site of the wound. On the other hand the non-resorbable sutures do not degrade, so there is a need to remove them after healing of the wound, unless they are being used as a permanent implant.
Surgical suture material usable for wound closure comprises non-absorbable and absorbable materials. Absorbable surgical sewing threads based on natural biological materials, particularly cat gut and absorbable synthetic threads are known. Absorbable synthetic suture material can inter alia be produced from polyglycolic acid (PGA). In the physiological environment the sewing threads undergo a hydrolysis. The 50% breaking strength loss, also known as the half-life period, serves as a measure for the hydrolytic decomposition of the polymer material. Surgical sewing threads formed from braided PGA multifilaments (e.g. obtainable under the trademark DEXON) within 21 days have a 50% breaking strength loss and an absorption of hydrolyzates within 100 to 120 days. A multifilament sewing thread produced from a glycolide-lactide copolymer with a comonomer ratio of 90:10 has similar characteristics (obtainable under the trademark VICRYL). In vivo, after 25 days it loses 50% of its initial strength and is absorbed after more than 80 days.
What is needed is bioabsorbale sutures with improved strength having increased 50% breaking strength.